The epidermis of petals can teach us a lot about light absorption. Because flowers rely upon strong colour impressions to attract pollinating insects, they have adapted epidermises which consist of densely-packed microstructures, ribbed by nanostructures, which allow them to absorb the broadest spectrum, while letting only coloured light escape. This is especially true of roses.
Following this principle, scientists at the start-up Phytonics, which is a spin-off from the Karlsruhe Institute of Technology (KIT), have developed a flexible, anti-reflective “Phytonic foil” that can be wrapped around surfaces to improve the solar absorption of photovoltaic (PV) modules by up to 10 percent. "Our film makes it possible to combine the advantages of high-gloss and matt surfaces, namely to achieve intensive colours without disturbing reflections," explains the co-founder Dr Ruben Hünig in a from KIT.
The foil, which has been seven years in the making, almost completely supresses reflection for all wavelengths and angles of incidence by replicating the epidermis structures inside rose petals. It can be easily applied to flat or curved surfaces and gives an intensely-coloured, “velvety” appearance. It is hoped the innovation will not only improve the performance of PVs but also their popularity for use on facades and display panels.
The Phytonic foil has practical advantages too: it is dirt-repellent and highly resistant to environmental influences such as UV light, moisture and temperature fluctuations; and it can be manufactured using roll-to-roll printing and applied using a lamination process.
From 2021, Phytonics will receive funding from the Federal Ministry for Economic Affairs and Energy and the European Social Fund (ESF).